Add test to validate getTime and time fields in _stats API response

getTime and time fields are verified to be included in the _stats API response and correctly aligned.

Signed-off-by: hye-on <ain0103@naver.com>

rest-api-spec/src/main/resources/rest-api-spec/test/indices.stats/60_time_fields.yml.yml

@@ -0,0 +1,32 @@
+---
+setup:
+  - do:
+      indices.create:
+        index: test1
+        body:
+          settings:
+            number_of_shards: 1
+            number_of_replicas: 0
+        wait_for_active_shards: all
+
+  - do:
+      index:
+        index: test1
+        id: 1
+        body: { "foo": "bar" }
+
+  - do:
+      indices.refresh:
+        index: test1
+
+---
+"Test _stats API includes both time and getTime metrics with human filter":
+  - do:
+      indices.stats:
+        metric: [ get ]
+        human: true
+
+  - is_true: _all.primaries.get.time
+  - is_true: _all.primaries.get.getTime
+  - match: { _all.primaries.get.time: "0s" }
+  - match: { _all.primaries.get.getTime: "0s" }